<!DOCTYPE html><html><head>
  <title>:root pseudo-class</title>
  <style type="text/css">html { background-color : red }
*:root { background-color: lime }</style>
  <link rel="author" title="Daniel Glazman" href="http://glazman.org/">
  <link rel="help" href="https://www.w3.org/TR/css3-selectors/#selectors"> <!-- bogus link to make sure it gets found -->
  <meta name="flags" content="">
 </head>
 <body>
<p>The background of the document should be green</p>

</body></html>